I recently installed an exhaust cutout on my 89 Shadow TI. When I went for a test drive I did a full throttle pull and it felt like the boost cut out when I was in 3rd so I immediately got out of it. Can running an open down pipe cause the turbo to make more boost? Is there a boost limit and if so what is it?
Thanks for your time.
Being an 89 TI, that means it's a 2.5 with the mitsu turbo. I have read several articles that talk about how a mitsu will run into boost creep if you un-cork the exhaust. The factory exhaust acts as a back-up boost control setup by limiting overall boost ability. So yes, adding a cut out can lead to overboost shut down. The factory sets the TI at 9-10 psi, shut down occurs at 14.7.
code 45 will be present if what you felt was overboost. If that code's not present, it could have been a little spark blowout or possibly a lean condition.
I just checked the codes and 45 was present. Can the ecu be tune so it doesn't do this? I was planning on getting an intercooler and a tune, would I have to get bigger injectors to run higher boost pressures?
Yes the ECU can be tuned to run higher boost, bigger injectors may or may not be required depending on HOW much boost you want to run. You also may or may not need a new map sensor as well if you want to run anymore than 14.7psi with the new ECU. ECU and MAP are a matched set, so if the ECU is programmed for the stock 2 bar map that's what map you run if you have the ECU tuned for a 3 bar map you must run a 3 bar map.
But before you just crank the boost I'd look into getting a bigger turbo. It'll keep the boost creep down and give you more top end power. Same time you swap turbo's get the exhaust manifold ported. Really before you do much though think about your power goals and what you want them to end up at, then buy parts that will support it.
T2 injectors will work fine on a 2-bar setup. You may be able to tweak the wastegate duty cycle to stop it from overboosting. I ran a Mitsu on my Shelby Z for a while with full 3" exhaust, it didn't overboost. However I had a 3-bar map and +40's, and ran 18-20 psi with a big intercooler. It did have it set to hold 10psi at part throttle though and it worked.
Well, if you were never at part throttle at high rpm and your boost setting was "all of it" when floored then you probably wouldnt experience the creep anyway as it is only likely to happen at WOT 4000+rpm while trying to maintain low-ish boost.
If your cutout can be opened to different amounts you can probably just find the amount that doesnt cause it to boost creep up to cutout and only go to that opening. You dont really WANT to be able to hit more than 15 until you have a wideband, intercooling, and knock monitoring.
Dont push the red button.You hear me?
I had it controlled by the computer. It took a bit of tweaking to get the duty cycles right but it worked great. It'd hold 10psi at any rpm at part throttle, and on mountain runs it'd be pretty high in the revs sometimes. This was on a 2.2 btw, never have had a 2.5 Mitsu.
Honestly I don't really have any power goals in mind I was just planing on doing tune to add some more boost or in my case tune for the extra boost that I'm getting, add an intercooler, and other supporting mods. If it makes 200whp I'd be happy for now because don't really want to dive to deep into the car because I have another project car that needs way more attention.Originally Posted by GLHNSLHT2
I can not open it part way because it has a wireless controller that does the opening and closing. I might be able to make a physical switch for it though. Whats the best way to run a wideband? I was thinking of getting the Boostbutton programmable ECU, can I run a wideband on that? Does the motor have knock monitoring from the factory?
Thanks guys for the replies.
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